The major objective of the proposed research is to investigate the role of the medial preoptic area (MPOA) in the regulation of maternal behavior. One goal of the project has been to show that the MPOA and its lateral connections are critical for estrogen facilitated maternal behavior in the rat. This goal has been achieved. MPOA lesions or knife cuts which severed the lateral connections of the MPOA severely disrupted maternal behavior. Cutting the dorsal or posterior connections of the MPOA produced either minor or no deficits in maternal behavior, but this was associated with hypoactivity and loss of body weight and probably represents a debilitation effect. We are currently investigating the possibility that descending axons which leave the MPOA from a lateral direction exert their influence on maternal behavior by regulating the activity of the cell bodies of dopamine neurons in the substantia nigra and ventral tegmental area.